Per default is seems that the "Generate Java Interface from WSDL file." generated classes in JAXB 2.2 format. Unfortunetly Java 6 still is bundled with JAXB 2.1 and the 2.2 format has some incompatibilities.

But since 2.2 is backward compatible with 2.1 it would be a great simplification (not need to mess with endorsed dirs) if the generator would support a selection for what JAXB version target the java files should be generated for (e.g. 2.0, 2.1, 2.2, etc.). Most generators shoudl actually have an option for that.